1. Field of the Invention
The present invention relates generally to apparatus and method for providing cardiac support during cardiac surgery. More particularly, the present invention relates to such apparatus and method for providing cardiac support which are less traumatic and invasive.
2. Description of the Related Art
When it is necessary to perform cardiac surgery, surgery has heretofore been accomplished by major open-heart surgical procedure, requiring general anesthesia and full cardio-pulmonary bypass (CPB). Such surgery usually includes about three weeks of hospitalization and months of recuperation. Average mortality rate for this procedure is approximately 1% with complication rate being substantially higher. Descriptions of open heart procedure can be found in Gibbon's Surgery of the Chest 5th Edition, (David C. Sabiston, Jr., M.D., Frank D. Spencer, M.D. 1990, Vol. 11, Ch. 52, pp. 1, 56-61, 596, and Textbook of Interventional Cardiology, Eric. J. Topol, 1990, Chs. 43-44, pp. 831-867).
Coronary artery bypass graft (CABG) procedure is one type of open chest surgical technique used to treat coronary artery disease. During the CABG procedure, the patient's sternum must be opened with the chest spread apart to provide access to the heart. The patient's blood is cooled and diverted from the patient's lung to an artificial oxygenator. A source of arterial blood is then connected to a coronary artery downstream from the occlusion while the patient undergoes cardiac arrest and is supported by a CPB circuit. The source of blood is often the left or right internal mammary artery and the target coronary artery is the anterior or posterior arteries which might be narrowed or occluded.
While very effective in many cases, the use of open chest surgery is very traumatic to the patient. The procedure requires immediate post-operative care in an intensive care unit. The total period for hospitalization may be seven to ten days, while the total recovery period may be as long as six to eight weeks. In addition, open-heart procedure requires the use of CPB which continues to represent a major assault on a host of body systems. For example, in up to 24% of the open chest coronary artery bypass surgeries performed in the United States, there is a noticeable degradation of the patient's mental faculties following such surgeries. This degradation is commonly attributed to cerebral arterial blockage from debris and emboli generated during the surgical procedure.
In addition, much post-operative morbidity, and ome mortality, is attributed to the shortcomings of PB.